First time for me on this job. I'm not at all surprised that this has developed due to all the severe overheating that I had to battle with the glazed water pump pulley and high altitude towing in 100 degree weather. Arizona Highway 89 southbound into Flagstaff is the ultimate testing ground for gauging how well your cooling system works.
Anyway..... Spotted the telltale signs of engine oil entering the cooling system and I'm wondering if there's anything that I should watch for other than just getting in there to detach the oil cooler assembly from the side of the block and replace the seals and then getting it back in there.

 

I think the center cooler section failures are kind of rare, but for piece of mind you can pressure test the tubes to be sure no leaks there. I've been seeing some pitting in the housings of some members recent repairs. Outside of having a replacement on hand, there's not much to do until it's off and confirmed. I'll also say that, although it isn't necessary, unbolting the power steering bracket and laying it over in the battery box area opens up a lot of access to the front housing. It's only a matter of a few bolts to move the alternator a few more on the bracket. Leave the hoses attached and just tie it out of the way.

 

Speaker of pressure testing the cooler seen this on Facebook yesterday.



If it were me I would just go ahead and replace the oil cooler as well. When mine started that I tried to cheap it and just replaced o rings with Motorcraft and flushed it good and then a week later oil in coolant again sane way as before. So got new o rings again and replaced cooler as well and flushed good yet again and it's been fine ever since.

 

about a year ago, I just up and bought a brand new Oil Cooler, it is still in the box.
( there was a scare on at the time, that they would be discontinued, and I don't like that )

I figure that if it is needed to be cleaned, then a new one can go on "right now", and then I can take the OEM unit apart, and boil it out until no traces of oil or coolant is in the tubes.

and, be able to test it for leaks...
hopefully, it will pass and make me a spare.

if needed.

 

Thank you all for the replies, gentlemen. It's going to be a couple of weeks before I get to this job at best due to other, more pressing needs, but I will get back to you all with what I found. Before I buy an oil cooler, I'm taking the assembly out and scrutinize the o-rings for signs of tearing and/or loosing their elasticity from all the overheating that this poor engine had to endure. It never boiled over, but the gauge ran hot way more times than I would like to count. And I'm glad that it shows no signs of being worse for wear over it. No excess blow-by, uneven cranking, etc. Starts right up and idles perfectly level from the first seconds of operation.

 

Is it seeping/dripping oil externally onto the outside of the cooler? If it's never been done before it's just one of those things. I got the O-rings and gaskets from the local Ford parts counter and did mine about a year and a half ago. Wasn't internally leaking (yet) but the seals were pretty tired and seepage was well under way externally. Re-used the cooler itself and it's been fine so far. Sometimes they rust out but I doubt that's a problem where you live. Getting it apart is easy by tapping on the headers with a rubber mallet but back together is a little tricky. You're not going to press it back together by hand and the headers have to be clocked right. I made some witness marks with a blade so it went back together the same way and used a 1" ratchet strap wrapped around the ends and then a rubber mallet or dead blow. The tightened strap applies a constant tension and then the taps with the mallet seats them. Use a light coat of motor oil or dielectric grease on the rings and inside of the headers. Oil filter has to come off so you'll need a new one of those. The two bolts on the front are hard to get to without removing other stuff but not impossible. Everything on the oil filter housing end is wide open. Catch it quick enough and it shouldn't make too big of a mess of the cooling system.

 

Mine ran way cooler out to SW Washington with the new Motorcraft fan clutch via ND, MT, ID, OR...some pretty assholish wide open terrain in the heat and wind to struggle across for those familiar. Yes there was a little MPG penalty compared to the Hayden I had on there but it's clearly a more severe duty unit. I never saw an EOT higher than 219 which is at least 10 lower if not more than it would have been.

 

Thank you, this is good information.

What my biggest problem turned out to be was that idiot pulley had become too slick to gain any traction and actually spin the water pump, let alone the engine fan. Now that I have that squared away I find that the Hayden works just fine under any conditions, but I haven't tested it on that 7,000 foot highway coming down into Flagstaff on a hot day pulling the trailer. There's some good hills near where I live, but nothing like that one stretch of road to really tax the cooling system. It's like the I-90 coming up out of Vantage on the Columbia River where they have signs telling drivers to turn off the AC to prevent boilover, but at 7,000 foot elevation.

 

I wonder if there is a way to rejigger our factory oil coolers so they don't rely on limited-lifespan o-rings to keep the liquids separated. Braze it together perhaps?

 

No, then it would be a rigid structure, far more vulnerable to stress cracking from expansion and contraction due to temperature fluctuations. What we have is really the best solution. I don't fault mine giving out so soon compared to other vehicle's lifespans. What I have in this truck is a 4.88 rear axle geared road tractor that does 2500 rpm at 68 mph that suffered multiple overheating sessions in the past three years. I'm grateful it never go to hot that it boiled over. Soon as I pulled over at a rest area and turn on high idle, or slow way down and drop it into third gear while feathering the throttle, less than five minutes later all would be restored. It was real hit or miss, most times it would work just fine, but other times it acted like there was grease on that pulley and the water pump simply wasn't being driven at the speeds that the engineers intented it to. And then it would get hot.

 

Does anyone recommend using a flap disk to smooth the small pitting where the gaskets sit, or is it time to suck it up and buy a new one? I just replaced the o-rings a year ago (from RiffRaff) and I am seeing oil in my degas bottle. At first I thought it might be residual from an incomplete flush, but its gotten to the point where its looking bad.
No leaking on the outside of the cooler though. If it IS leftover from a flush, would a coolant filter setup take care of it?

 

There is a guy on Facebook that cuts and mods the end caps to an fittings to run external air to air oil coolers with a fan. Supposedly they work very well compared to factory setups.

 

There is a "paper" made to soak up oil, I bought it on Amazon.


take strips of it, and place them in the DeGas bottle with a string so you can pull them out.
they are darn good to place on the floor under your truck for drips.

 

I didn’t go that way this time but yeah that one seems to go on forever. I cut down 395 to 82 and went into Portland on 84 and up 5 to Lazy days RV in Woodland, WA. Actually I cut across I-205 from 84 to 5.

well the pulley would be separate problem but I’ve got EOT data and real world fan behavior on the back to back fan clutch shootout. The results are in on that one and the Motorcraft wins easily.

I had a badly worn pulley once a long time ago that would start to slip at higher RPM like say coming DOWN a grade in a lower gear to get some engine braking, and simply putting a new one on fixed that. Now I just replace them with the pump since it’s a relatively inexpensive part.

 

Rubber gets old and dries out which doesn't help its sealing properties. Put that next to heat and life expentancy goes way down. I slowly updated my o-rings to viton as they started to leak to maximize the time before the next leak.

I got my reseal kit from Bob (https://dieselorings.com/products/15...ate-94-03-7-3l) but don't know if they were viton or not.

I definitely second Bob's recommendation for taking both flanges off so you're not doing all the work on your back and in a restricted space. It is not hard to roll an o-ring and be back at it in short order to fix the error.

I used o-ring lube to minimze the change of rolling one and used a ratchet strap to help install and seat the end caps.